| 摘要 |
The halo-suppressing thin film (32) is made, of the CRT, of magnesium difluoride and has a refractive index (NM) is 1.38. The face plate (14) is made of sapphire having a refractive index (nf) of 1.8, and the luminescent screen (16) has a refractive index (np) of 2.3. The critical angle for total internal reflection from the interface is reduced to thirty-seven degrees of arc compared with fifty-two degrees for a prior arrangement. - The thickness of the intermediate layer exceeds one half wavelength of light emitted by the screen to prevent interference. A layer of thickness 0.8 micron reduces halo intensity by a factor of three whilst doubling image brightness. Alternatively, the suppression film is included as part of an eight-layer interference filter.
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